Ionic4 leaflet request delay/latency

I have a very basic mapping application using ionic4 / leaflet and functionally it is working. However I notice a significant delay on loading basemap tiles when in app compared to in my desktop dev environment. The images load almost instantly on desktop versus there being noticable delay in app.

The exact same embedded image e.g.

<img src="https://c.tile.opentopomap.org/4/15/5.png">

Takes 55ms on a desktop browser vs 420ms in app.

In Dev/Desktop
In App (taken with chromes remote devices dev tool)

What explains the 230ms “connection start” in the app? Is this related to ionic or the webview in any way and is there a way to circumvent this? It is very noticeable and makes the performance of the app look much worse than it actually is.

The app itself is just a very basic leaflet application

<div id="map" style="width: 100%; height: 100%"></div>

this.map = Leaflet.map("map", {
    center: [this.latitude, this.longitude],
    zoom: 6,
    minZoom: 3,
    maxZoom: 17,
    inertiaDeceleration: 1000,
    attributionControl: false,
    zoomControl: false,
    maxBounds: Leaflet.latLngBounds([-90, -180],[90, 180])
});

const basemap = Leaflet.tileLayer('https://{s}.tile.opentopomap.org/{z}/{x}/{y}.png',  {
    maxZoom: 17,
    minZoom: 0
});

basemap.addTo(this.map);

Using “leaflet”: “^1.5.1”

Ionic:

Ionic CLI : 5.4.2 (/usr/local/lib/node_modules/ionic)
Ionic Framework : @ionic/angular 4.7.4
@angular-devkit/build-angular : 0.801.3
@angular-devkit/schematics : 8.1.3
@angular/cli : 8.1.3
@ionic/angular-toolkit : 2.0.0

Cordova:

Cordova CLI : 9.0.0 (cordova-lib@9.0.1)
Cordova Platforms : android 8.1.0
Cordova Plugins : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.1.2, (and 6 other plugins)

Utility:

cordova-res : not installed
native-run : 0.2.8

System:

Android SDK Tools : 26.1.1 (/home/anthony/Android/Sdk)
NodeJS : v12.11.1 (/home/anthony/.nvm/versions/node/v12.11.1/bin/node)
npm : 6.11.3
OS : Linux 5.0